1. Field of the Invention
The present invention is related to processes for fault isolation and, more particularly, relates to a method which may be used as part of a fault isolation process for facilitating faster and more accurate fault isolation.
2. Related Art
Fault isolation typically refers to the process of identifying a faulty component(s) in a system. An engineer typically performs the isolation, possibly with the aid of an automated system. More specifically, when a problem with machinery is detected, a customer typically contacts a service office, and the service office dispatches an engineer to the customer location. The engineer then performs a series of tests in an attempt to isolate the fault. The sequence of testing and the components actually tested usually are determined by the engineer. The amount of time required to isolate the fault and the accuracy of the fault isolation therefore are highly dependent upon the experience and skill of the engineer, and on the complexity of the machinery.
In large and complex systems, components which compose the system typically include respective electronic sensors and respective error detection units. The respective error detection units generate respective error codes when respective sensors detect abnormalities. The error codes are sometimes referred to herein as fault codes, fault messages, error messages, etc. The error codes alert an operator as to potential faulty conditions within the system, and each error code, for example, corresponds to a specific condition or set of conditions, e.g., "temperature of the system is above normal". Analysis of a listing, e.g., a print-out listing or display, of these error codes typically is the starting point for the engineer.
Isolating faulty components of a complex system composed of many components, e.g., thousands of components, can be a very time consuming and difficult task. In an effort to reduce the amount of time necessary for fault isolation, expert systems have been used in fault isolation processes. In general, the effectiveness with which an expert system can isolate a fault improves with an increase in the number of symptoms or initial data available about the problem. If the number of symptoms becomes large for a specific malfunction or if extraneous information caused by side-effects of the real problem are introduced, however, the information must be filtered prior to analysis. Even subsequent to filtering, many error codes may remain. Modeling the rules and logical connections in an expert system in view of the large number of possible error codes is an astronomical task. Even if the rules could be modeled in an expert system, the response time of the expert system may be too slow and the diagnostic quality may not be high as a result of the complexity involved in creating and processing the rule model. Maintenance and future enhancements of such expert systems also poses difficulties.
Although automation techniques are believed to have great utility in fault isolation, there exists a need for a system which is simple yet provides accurate fault isolation, even in the presence of generation of a large number of error messages/codes.
Further, in order to reduce the amount of time required by an engineer to perform fault isolation, it would be desirable to provide an automated system which can utilize the error code listing to identify tests which the engineer should perform in fault isolation. Preferably, the tests would be identified before the engineer arrived at the site so that upon arrival, the engineer immediately could begin testing operations to isolate the fault.